(1,09 Mb)6.19. Subarachnoid hemorrhage
What is the risk of spontaneous rupture in patients with intact intracerebral aneurysm?
In patients with intact intracerebral aneurysm, does the procedure on the malformation (via surgery or via an endovascular approach) reduce the risk of presenting subarachnoid hemorrhage?
SAH accounts for a relatively small percentage of all strokes (between 1% and 7%). However, its impact on overall morbimortality is very high, given that it affects people who are relatively young; it has a very poor prognosis238. The incidence non-traumatic SAH ranges from 6-25 cases per 100,000 inhabitants. The highest rates correspond to studies performed in Finland and Japan485-488. A SR (3,936 patients) explored the relationship of several factors and the risk of SAH. High blood pressure values (RR: 2.5; 95% CI: 2.0 to 3.1), alcohol consumption (>150 mg/d) (RR: 2.1; 95% CI: 1.5 to 2.8) and smoking (RR: 2.2; 95% CI: 1.3 to 3.6) were consistently associated with a significantly higher risk of SAH69.
observational
studies
Observational
studies
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The main cause of SAH is a ruptured intracranial aneurysm (80%), while the remaining 20% corresponds to arteriovenous malformations, tumours, blood dyscrasias, central nervous system infections, use of drugs or to an unknown cause489. Although it has been suggested that there could be a genetic component, most SAHs are caused by lifestyle-related risk factors. The estimated prevalence of aneurysm pathology in the population ranges between 1% and 6%, with a mean annual rupture risk of 0.7%. 10% to 30% of cases are multiple490.
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Intracranial aneurysms are a result of weakness in an artery’s vascular wall and interaction with hemodynamic factors such as HT, which can lead to growth and rupture of the aneurysm491, 492. When an intracranial aneurysm is located, therapeutic strategies should be aimed at preventing hemorrhage due to aneurysm rupture. Currently available options are the management of risk factors associated with hemorrhagic stroke and a surgical approach to the aneurysm sac.
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6.19.1. Perform surgery or wait?
A SR that included 4,705 patients with intact aneurysms reported that certain patient characteristics, such as age older than 60 years or female gender, were associated with an increased risk of a ruptured aneurysm (RR: 2.0; 95% CI: 1.1 to 3.7 and RR: 1.6; 95% CI: 1.1 to 2.4 respectively)493. The aneurysm’s characteristics, posterior localisation or size larger than 5 mm were associated with a significantly higher rupture risk (RR: 2.5; 95% CI: 1.6 to 4.1 and RR: 2.3; 95% CI: 1.0 to 5.2 respectively).
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There are no trials comparing any type of procedure performed on the aneurysm sac versus expectative attitude and it is unlikely that this type of studies will be designed in the future. Because of this, the available evidence is based on data yielded by the few observational studies that are described in the natural history of this pathology. Other factors to be taken into account when the time comes to decide between one or the other option are, for instance, the presence of neurological symptoms in the absence of bleeding, generally due to pressure or the mass effect; the patient`s age which determines prognosis following surgery or the reference values of the patients whom upon diagnosis may experience a deterioration in their quality of life.
The ISUIA cohort study (International Study of Unruptured Intracranial Aneurysms) has been the most relevant up until now. The study described the natural history of unruptured intracranial aneurysms and the risk related to the surgical procedure or endovascular procedure in a cohort of 4,060 patients494. The natural course, with no operation, in people with an unruptured aneurysm shows that the risk of rupture at 5 years for an anterior circulation aneurysm is 0% (for those with a size < 7 mm), 2.6% (7 to 12 mm), 14.5% (13 to 24 mm) and 40% (> 25 mm). The risk of rupture is different for posteriorly located aneurysms, being at 5 years 2.5% (for those with a size< 7 mm), 14.5% (7 to 12 mm), 18.4% (13 to 24 mm) and 50% (> 25 mm).
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Surgery versus endovascular procedures
The risks in patients who underwent a surgical or endovascular procedure were also high. 6% of patients who underwent surgery presented a rupture aneurysm, 4% cerebral hemorrhage and 11% had a stroke during the procedure. The complications of endovascular treatment were cerebral hemorrhage (2%) and stroke (5%) during the procedure. In patients with intact aneurysm who underwent surgery, the main risk factors for poor clinical evolution after surgery were age older than 50 years (RR: 2.4; 95% CI: 1.7 to 3.3), diameter larger than 12 mm (RR: 2.6; 95% CI: 1.8 to 3.8), posterior localisation (RR: 1.6; 95% CI: 1.1 to 2.4) and prior ischemic stroke (RR: 1.9; 95% CI: 1.1 to 3.02).
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In patients who underwent endovascular treatment, aneurysm diameter greater than 12 mm (RR: 2.4; 95% CI: 1.0 to 5.9) and posterior localisation (RR: 2.25; 95% CI: 1.1 to 4.4) were factors associated with poor clinical evolution after the procedure494. Complications after the endovascular procedure or surgery have been reported by case series or retrospective cohort studies. A recent cohort of individuals treated for intact intracerebral aneurysm (2,535 patients) reported a lower rate of complications related with the endovascular procedure (6.6%) when compared to surgical procedure (13.2%), as well as lower mortality (0.9% versus 2.5% respectively)495.
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Summary of the Evidence
| 2++ | High blood pressure values, alcohol consumption and smoking have been associated with an increased risk of SAH 69. |
| 2++ | The main cause SAH is a ruptured intracranial aneurysm. Rupture risk increases with aneurysm size493. |
| 2++/2+ | The endovascular procedure presents a lower rate of complications than the surgical procedure494, 495. |
| 2++ | Factors associated with poor prognosis after the intervention are age, female gender, intervention on a large aneurysm and posterior localisation494. |
Recommendations
| √ | All patients with intact intracerebral aneurysm should be provided with adequate advice promoting healthier lifestyles, such as the cessation of smoking, alcohol consumption and use of any substance with sympatheticomimetic activity. |
| A | Patients with intact intracerebral aneurysm should maintain blood pressure values within the normal range. |
| B | In aneurysms whose size is equal to or bigger than 7 mm, a procedure on the aneurysm sack (via surgery or an endovascular procedure) and individual assessment of the risks of each intervention, the patient’s age, mass effect and localisation of the aneurysm should be be taken into account. |
| B | Expectative attitude is recommended in people over the age of 65, without symptoms and with anterior circulation aneurysms of less than 7 mm in diameter |
| B | In case of adopting a conservative approach, changes in size or presentation of the aneurysm should be closely monitored. |
Section 06 Bibliography
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- 490. Van Crevel H, Habbema JD, Braakman R. Decision analysis of the management of incidental intracraneal saccular aneurysms. Neurology. 1986;36:1335-9.
- 491. Ferguson GG. Physical factors in the initiation, growth, and rupture of human intracranial saccular aneurysms. J Neurosurg. 1972;37:666-77.
- 492. Sekhar LN, Heros RC.Origin, growth, and rupture of saccular aneurysms: a review. Neurosurgery. 1981;8:248-60.
- 493. Wermer MJ, van der Schaaf IC, Algra A, Rinkel GJ. Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke. 2007;38(4):1404-10.
- 494. Wiebers DO, Whisnant JP, Huston J 3rd, et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. 2003;362:103-10.
- 495. Higashida RT, Lahue BJ, Torbey MT, Hopkins LN, Leip E, Hanley DF. Treatment of unruptured intracranial aneurysms: a nationwide assessment of effectiveness. AJNR Am J Neuroradiol. 2007;28(1):146-51.
Latest update: Enero 2009
